Influence on grid frequency caused by restriction of PFR

All of the synchronize and close sets can take part in whack frequency modulation when the active power of system unbalance. However, some area's unit of the grid is being in the repairing period or many water area are in the dry season etc., these reasons have limited the capacity of PFR. Since hydropower plants and thermal power plants have their own unique characteristics, so when the primary frequency capacity is restricted, the frequency characteristics of grid is different. In addition, differences in plant location which determines the nature of its load in the region. This article analyzes the influence on grid frequency caused by restriction of PFR and the relationship between the frequency response and the capacity of PFR.